/*
 * This file contains code from "C++ Primer, Fourth Edition", by Stanley B.
 * Lippman, Jose Lajoie, and Barbara E. Moo, and is covered under the
 * copyright and warranty notices given in that book:
 *
 * "Copyright (c) 2005 by Objectwrite, Inc., Jose Lajoie, and Barbara E. Moo."
 *
 *
 * "The authors and publisher have taken care in the preparation of this book,
 * but make no expressed or implied warranty of any kind and assume no
 * responsibility for errors or omissions. No liability is assumed for
 * incidental or consequential damages in connection with or arising out of the
 * use of the information or programs contained herein."
 *
 * Permission is granted for this code to be used for educational purposes in
 * association with the book, given proper citation if and when posted or
 * reproduced.Any commercial use of this code requires the explicit written
 * permission of the publisher, Addison-Wesley Professional, a division of
 * Pearson Education, Inc. Send your request for permission, stating clearly
 * what code you would like to use, and in what specific way, to the following
 * address:
 *
 *  Pearson Education, Inc.
 *  Rights and Contracts Department
 *  75 Arlington Street, Suite 300
 *  Boston, MA 02216
 *  Fax: (617) 848-7047
*/

#include "MS_Queue.h"
#include <stdexcept>
using std::out_of_range;
#include <iostream>
using std::ostream;

//web-comment-begin

template <class Type>
void
Queue<Type>::copy_elems(const Queue& orig)
{
	// copy elements from orig into this Queue
	QueueItem* pt = orig.head;
	while (pt) {     // last element has next pointer == 0
		push(pt->item);  // copy the element
		pt = pt->next;   // get the next one from orig
	}
}

template <class Type>
Queue<Type>& Queue<Type>::operator=(const Queue& rhs)
{
	if (this != &rhs) {
		// destroy elements on this Queue
		destroy();
		copy_elems(rhs);    // copy from rhs into left-hand Queue
	}
	return *this;
}

template <class Type>
void
Queue<Type>::destroy()
{
	while (!empty())
		pop();
}


template <class Type>
void Queue<Type>::push(const Type& val)
{
	// allocate a new QueueItem object
	QueueItem* pt = new QueueItem(val);

	// put item onto existing queue
	if (empty())
		head = tail = pt;   // queue has only one element
	else {
		tail->next = pt;     // add new element to end of queue
		tail = pt;
	}
}

//begin{pop-defn}
template <class Type>
void Queue<Type>::pop()
{
	// pop is unchecked: popping off an empty Queue is undefined
	QueueItem* p = head;     // keep pointer to head so can delete it
	head = head->next;       // head now points to next element
	delete p;                // delete old head element
}
//end{pop-defn}

template <class Type>
ostream& operator<<(ostream& os, const Queue<Type>& q)
{
	os << "< ";
	typename Queue<Type>::QueueItem* p;
	for (p = q.head; p; p = p->next)
		os << p->item << " ";
	os << ">";
	return os;
}

